Conventional oven door assembly carts may carry seven or eight oven doors, each of which may weigh approximately 30-40 lbs. The lowest door supported by the conventional oven door assembly carts commonly is low to the floor (e.g., less than 30 inches from the floor), while the highest part commonly is supported high above the floor (e.g., greater than 60 inches above the floor). Thus, an operator of the cart commonly may need to load the 30-40 lb doors onto the cart, or unload the 30-40 lb doors from the cart, from a low position near the floor (e.g., less than 30 inches from the floor). Similarly, the operator of the cart commonly may need to load the 30-40 lb doors onto the cart, or unload the 30-40 lb doors from the cart, from a high position above the floor (e.g., greater than 60 inches from the floor). However, assembly workers commonly are not required to reach too high nor too low to remove a door from the cart due to ergonomic factors. As a result, many conventional assembly carts are designed or constrained such that an operator does not position a door on the cart at a position or height that is outside an acceptable vertical ergonomic working zone. Such design constraints ordinarily limit the number of doors that may be carried by each conventional cart. For example, a conventional cart commonly may be structurally capable of holding seven or eight doors stacked or positioned one above the other on the cart. However, due to the ergonomic design constraints mentioned above, many conventional carts may be designed or constrained such that the cart only is capable of supporting a lesser amount of doors (e.g., six doors) or such that an operator uses less than the total number of available door supporting positions/locations of the cart. Such a limitation of the number of doors carried by the cart below the actual structural capabilities of the cart may adversely impact the efficiency of the manufacturing process.